Feature/renderer performance (#24)

src/main/runtime/subtitle-prefetch-init.ts

@@ -0,0 +1,83 @@
+import type { SubtitleCue } from '../../core/services/subtitle-cue-parser';
+import type {
+  SubtitlePrefetchService,
+  SubtitlePrefetchServiceDeps,
+} from '../../core/services/subtitle-prefetch';
+import type { SubtitleData } from '../../types';
+
+export interface SubtitlePrefetchInitControllerDeps {
+  getCurrentService: () => SubtitlePrefetchService | null;
+  setCurrentService: (service: SubtitlePrefetchService | null) => void;
+  loadSubtitleSourceText: (source: string) => Promise<string>;
+  parseSubtitleCues: (content: string, filename: string) => SubtitleCue[];
+  createSubtitlePrefetchService: (deps: SubtitlePrefetchServiceDeps) => SubtitlePrefetchService;
+  tokenizeSubtitle: (text: string) => Promise<SubtitleData | null>;
+  preCacheTokenization: (text: string, data: SubtitleData) => void;
+  isCacheFull: () => boolean;
+  logInfo: (message: string) => void;
+  logWarn: (message: string) => void;
+}
+
+export interface SubtitlePrefetchInitController {
+  cancelPendingInit: () => void;
+  initSubtitlePrefetch: (externalFilename: string, currentTimePos: number) => Promise<void>;
+}
+
+export function createSubtitlePrefetchInitController(
+  deps: SubtitlePrefetchInitControllerDeps,
+): SubtitlePrefetchInitController {
+  let initRevision = 0;
+
+  const cancelPendingInit = (): void => {
+    initRevision += 1;
+    deps.getCurrentService()?.stop();
+    deps.setCurrentService(null);
+  };
+
+  const initSubtitlePrefetch = async (
+    externalFilename: string,
+    currentTimePos: number,
+  ): Promise<void> => {
+    const revision = ++initRevision;
+    deps.getCurrentService()?.stop();
+    deps.setCurrentService(null);
+
+    try {
+      const content = await deps.loadSubtitleSourceText(externalFilename);
+      if (revision !== initRevision) {
+        return;
+      }
+
+      const cues = deps.parseSubtitleCues(content, externalFilename);
+      if (revision !== initRevision || cues.length === 0) {
+        return;
+      }
+
+      const nextService = deps.createSubtitlePrefetchService({
+        cues,
+        tokenizeSubtitle: (text) => deps.tokenizeSubtitle(text),
+        preCacheTokenization: (text, data) => deps.preCacheTokenization(text, data),
+        isCacheFull: () => deps.isCacheFull(),
+      });
+
+      if (revision !== initRevision) {
+        return;
+      }
+
+      deps.setCurrentService(nextService);
+      nextService.start(currentTimePos);
+      deps.logInfo(
+        `[subtitle-prefetch] started prefetching ${cues.length} cues from ${externalFilename}`,
+      );
+    } catch (error) {
+      if (revision === initRevision) {
+        deps.logWarn(`[subtitle-prefetch] failed to initialize: ${(error as Error).message}`);
+      }
+    }
+  };
+
+  return {
+    cancelPendingInit,
+    initSubtitlePrefetch,
+  };
+}